U.S. patent number 5,448,369 [Application Number 08/195,012] was granted by the patent office on 1995-09-05 for apparatus for a high definition vcr which selects a video signal characteristic to be transmitted depending on characteristics of the tap and channel.
This patent grant is currently assigned to Goldstar Co., Ltd.. Invention is credited to Seung I. Kim, Choon Lee, Dong H. Lee, Tae S. Yang.
United States Patent |
5,448,369 |
Lee , et al. |
September 5, 1995 |
Apparatus for a high definition VCR which selects a video signal
characteristic to be transmitted depending on characteristics of
the tap and channel
Abstract
A signal characteristic variation apparatus for a high
definition VCR in which a characteristic of a video signal is
varied according to characteristics of a tape and a channel. A
predetermined frequency band of test signal is recorded on the tape
for recording the tape and channel characteristics in a recording
mode. This enables the video signal to be recorded on the tape in
the proper mode and permits, in the play-back mode, the tape and
channel characteristics to be discriminated by detecting the test
signal recorded on the tape. Therefore, the video signal can be
played back from the tape with its frequency characteristic
properly adjusted according to the discriminated tape and channel
characteristics.
Inventors: |
Lee; Dong H. (Seoul,
KR), Kim; Seung I. (Seoul, KR), Yang; Tae
S. (Seoul, KR), Lee; Choon (Seoul,
KR) |
Assignee: |
Goldstar Co., Ltd. (Seoul,
KR)
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Family
ID: |
27348920 |
Appl.
No.: |
08/195,012 |
Filed: |
February 14, 1994 |
Foreign Application Priority Data
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Feb 13, 1993 [KR] |
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2022/1993 |
Apr 30, 1993 [KR] |
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7454/1993 |
Apr 30, 1993 [KR] |
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7455/1993 |
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Current U.S.
Class: |
386/230; 360/32;
360/65; 386/269; 386/273; 386/314; 386/327; 386/328; 386/335;
386/E5.015; 386/E5.025; 386/E5.03 |
Current CPC
Class: |
H04N
5/9206 (20130101); H04N 5/9264 (20130101); H04N
5/9315 (20130101); H04N 17/06 (20130101); H04N
5/926 (20130101) |
Current International
Class: |
H04N
17/06 (20060101); H04N 5/926 (20060101); H04N
5/92 (20060101); H04N 5/931 (20060101); H04N
005/76 (); G11B 005/00 (); G11B 005/09 (); G11B
005/035 () |
Field of
Search: |
;358/310,335,342,320,323,327,328,330,336,337,340
;360/32,33.1,29,27,36.1,65 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0369756 |
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May 1990 |
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EP |
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0469861 |
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Feb 1992 |
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EP |
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4118533 |
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Dec 1992 |
|
DD |
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Other References
Minoru Yoneda et al., An Experimental Digital . . ., IEEE
Transactions on Consumer Electronics, vol. 37, No. 3, Aug. 1991,
pp. 275-282. .
Patent Abstracts of Japan, vol. 8, No. 86, Apr. 19, 1984. .
Patent Abstracts of Japan, vol. 12, No. 407, Oct. 27, 1988. .
JP-A-63-059287, Mar. 15, 1988. .
IEEE Transactions on Consumer Electronics, vol. 35, No. 3, Aug.
1989, pp. 450-457, C. Yamamitsu et al..
|
Primary Examiner: Chin; Tommy P.
Assistant Examiner: Tran; Thai
Claims
What is claimed is:
1. A signal characteristic variation apparatus for a high
definition video cassette recorder, comprising:
scaling means for selecting an output signal from an encoder or
output data from a decoder in a television receiver under control
of a first switch and formatting the selected signal or data into a
data stream;
variable length coding means for coding the output signal from said
encoder or motion data, control data and DCT coefficient data
output from said decoder at a variable length and outputting the
coded data to said scaling means;
scale control means for outputting a scale control signal to said
scaling means according to a selected one of recording modes;
error correction coding means for adding an error correction code
to an output signal from said scaling means;
formatting means for formatting an output signal from said error
correction coding means in a recording format on a tape;
channel modulation means for modulating an output signal from said
formatting means at a frequency band suitable to tape and channel
characteristics;
test signal generation means for generating a test signal in
response to a switching control signal which is generated according
to the selected recording mode and passing the generated test
signal at a predetermined frequency band, the test signal from said
test signal generation means being used to discriminate the tape
and channel characteristics;
recording amplification means for amplifying an output signal from
said channel modulation means or the test signal from said test
signal generation means by a predetermined level under control of a
second switch;
first and second heads for recording an output signal from said
recording amplification means on the tape;
third and fourth heads for playing back a video signal or the test
signal recorded on the tape in a playback mode;
playback amplification means for amplifying the video signal or the
test signal played back by said third and fourth heads by a
predetermined level;
tape characteristic detection means for receiving an output signal
from said playback amplification means under control of a third
switch and discriminating the tape and channel characteristics in
response to the received signal;
equalization means for compensating for distortion of the output
signal from said playback amplification means in response to a
first output signal from said tape characteristic detection
means;
channel demodulation means for demodulating an output signal from
said equalization means at a frequency band suitable to the tape
and channel characteristics in response to a second output signal
from said tape characteristic detection means;
deformatting and error correction decoding means for deformatting
an output signal from said channel demodulation means into the
original state and correcting an error of the resultant data
stream; and
inverse scaling means for performing inverse scaling of an output
signal from said deformatting and error correction decoding means
to extract motion data, the DCT coefficient data and the control
data therefrom and outputting the extracted data to said decoder in
said television receiver.
2. A signal characteristic variation apparatus for a high
definition video cassette recorder, as set forth in claim 1,
wherein said scaling means includes:
a demultiplexer for demultiplexing an output signal from said
encoder;
a fourth switch for selecting one of an output signal from said
demultiplexer and the DCT coefficient data from said decoder;
a fifth switch for selecting one of the output signal from said
demultiplexer and the control data from said decoder;
a sixth switch for selecting one of the motion data from the
decoder and a ground;
a DCT coefficient data arrangement unit for applying an output
signal from said fourth switch to said variable length coding means
and compressing the coded DCT coefficient data from said variable
length coding means in response to the scale control signal from
said scale control means;
a DCT coefficient data selector for removing unnecessary DCT
coefficient data from an output signal from said DCT coefficient
data arrangement unit in response to the scale control signal from
said scale control means;
a control data adjustment unit for applying an output signal from
said fifth switch to said variable length coding means, compressing
the coded control data from said variable length coding means in
response to the scale control signal from said scale control means
and adjusting a size of the compressed control data in response to
the output signal from said DCT coefficient data arrangement
unit;
a motion data adjustment unit for applying an output signal from
said sixth switch to said variable length coding means, compressing
the coded motion data from said variable length coding means in
response to the scale control signal from said scale control means
and adjusting a size of the compressed motion data in response to
the output signal from said DCT coefficient data arrangement
unit;
a multiplexer for multiplexing an output signal from said DCT
coefficient data selector and an output signal from said control
data adjustment unit; and
a formatter for formatting an output signal from said multiplexer
and an output signal from said motion data adjustment unit into the
data stream.
3. A signal characteristic variation apparatus for a high
definition video cassette recorder, as set forth in claim 1,
wherein said variable length coding means includes:
a control code table for storing control data code values for the
variable length coding;
a control data converter for converting an output code from said
control code table into control data and outputting the converted
control data to said scaling means;
a motion code table for storing motion data code values for the
variable length coding;
a motion data converter for converting an output code from said
motion code table into motion data and outputting the converted
motion data to said scaling means;
a DCT coefficient code table for storing DCT coefficient data code
values for the variable length coding; and
a DCT coefficient data converter for converting an output code from
said DCT coefficient code table into DCT coefficient data and
outputting the converted DCT coefficient data to said scaling
means.
4. A signal characteristic variation apparatus for a high
definition video cassette recorder, as set forth in claim 1,
wherein said test signal generation means includes:
a test signal generator for generating the test signal in response
to the switching control signal which is generated according to the
selected recording mode; and
a band pass filter for passing the generated test signal from said
test signal generator at the predetermined frequency band and
outputting the resultant test signal to said recording
amplification means through said second switch.
5. A signal characteristic variation apparatus for a high
definition video cassette recorder, as set forth in claim 4,
wherein said tape characteristic detection means includes:
a signal analyzer for discriminating the tape and channel
characteristics in response to the output signal from said playback
amplification means and controlling said scale control means in
accordance with the discriminated result;
a comparator for comparing a frequency characteristic of an output
signal from said signal analyzer with that of the test signal from
said test signal generation means and applying the second output
signal to said channel modulation means and said channel
demodulation means in accordance with the compared result to adjust
the frequency bands thereof; and
a tape characteristic measurement unit for detecting an error of
the played-back test signal in response to an output signal from
said comparator, varying a filter coefficient of said band pass
filter in said test signal generation means in such a manner that
the detected error becomes smaller than a predetermined threshold
value and outputting the varied filter coefficient as the first
output signal to said equalization means to determine a filter
coefficient thereof.
6. A signal characteristic variation apparatus for a high
definition video cassette recorder, as set forth in claim 1,
further comprising:
analog/digital conversion means for receiving an analog video
signal from a view finder of a camera or a camcorder and converting
the received analog video signal into a digital video signal;
said encoder encoding an output signal from said analog/digital
conversion means;
decoding means for decoding the motion data, the DCT coefficient
data and the control data from said inverse scaling means to expand
them into states before their compression; and
digital/analog conversion means for converting an output signal
from said decoding means into an analog signal and outputting the
analog signal to a monitor connected to said camera or
camcorder.
7. A signal characteristic variation apparatus for a high
definition video cassette recorder, as set forth in claim 1,
wherein said decoder in the television receiver extracts and
corrects an error inserted in the transmission and reception of the
video signal or generated in the recording and playback of the high
definition VCR.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a high definition video
cassette recorder (referred to hereinafter as VCR) connected to a
high definition television receiver, and more particularly to a
signal characteristic variation apparatus for the high definition
VCR in which a characteristic of a video signal transmitted is
varied according to characteristics of a tape and a channel for
recording and playback of the video signal.
2. Description of the Prior Art
Referring to FIG. 1, there is shown a block diagram of a
conventional high definition VCR connected to a high definition
television receiver. In this drawing, the high definition VCR is
designated by the reference numeral 20 and the high definition
television receiver is designated by the reference numeral 10. The
high definition television receiver 10 is adapted to receive a
compressed high definition video signal transmitted from a
broadcasting station and display the received video signal through
a monitor (not shown) thereof. The high definition VCR 20 is
adapted to record the high definition video signal received by the
high definition television receiver 10 on a tape, play back the
high definition video signal recorded on the tape and display the
played back video signal through the monitor of the high definition
television receiver 10.
The high definition television receiver 10 comprises a tuner 11 for
detecting the compressed high definition video signal Vi from the
broadcasting station, received through an antenna (not shown), a
demodulator 12 for demodulating the detected video signal from the
tuner 11 into a state before its modulation, a decoder 13 for
receiving the demodulated video signal from the demodulator 12
through a switch SW1 when the high definition television receiver
10 is selected by the user and decoding the received video signal
to expand it into a state before its compression, and a
digital/analog (D/A) converter 14 for converting the decoded video
signal from the decoder 13 into an analog video signal.
The high definition VCR 20 comprises an error correction coder 21
for receiving the demodulated video signal from the demodulator 12
through the switch SW1 when a recording mode of the high definition
VCR 20 is selected by the user and adding an error correction code
to the received video signal, a formatter 22 for formatting an
output signal from the error correction coder 21 in a recording
format on the tape, a channel modulator 23 for modulating an output
signal from the formatter 22 suitably to a channel characteristic,
a recording amplifier 24 for amplifying an output signal from the
channel modulator 23 by a predetermined level, and a head HD1 for
recording an output signal from the recording amplifier 24 on the
tape.
Also, the high definition VCR 20 comprises a head HD2 for playing
back a data stream of the video signal recorded on the tape when a
playback mode of the high definition VCR 20 is selected by the
user, a playback amplification/equalization circuit 25 for
amplifying the data stream played back by the head HD2 by a
predetermined level and compensating for a distortion of the
amplified data stream, a channel demodulator 26 for demodulating an
output signal from the playback amplification/equalization circuit
25 suitably to the channel characteristic, and a deformatter/error
correction decoder circuit 27 for deformatting an output signal
from the channel demodulator 26 into the original state, correcting
an error of the resultant video signal and outputting the
error-corrected video signal to the decoder 13 through the switch
SW1.
The operation of the conventional high definition VCR with the
above-mentioned construction will hereinafter be described.
First, in the case where the high definition television receiver 10
is selected by the user, the video signal compressed and modulated
in the broadcasting station is received by the antenna and then
tuned by the tuner 11. The tuned video signal from the tuner 11 is
demodulated into the state before its modulation by the demodulator
12. In the demodulator 12, there is extracted and corrected an
error component inserted into the video signal in the transmission.
The demodulated video signal from the demodulator 12 is applied to
the decoder 13 through the switch SW1.
the decoder 13 decodes the received video signal to expand it into
the state before its compression. The decoded video signal from the
decoder 13 is converted into the analog video signal by the D/A
converter 14 and then displayed through the monitor.
On the other hand, in the case where the recording mode of the high
definition VCR 20 is selected by the user, the switch SW1 is
switched to transfer the demodulated video signal from the
demodulator 12 to the error correction coder 21. The error
correction coder 21 adds the error correction code to the
demodulated video signal from the demodulator 12 to remove an error
component to be generated in the recording of the video signal on
the tape. Then, the formatter 22 formats the output signal from the
error correction coder 21 in the recording format on the tape.
The output signal from the formatter 22 is modulated by the channel
modulator 23 suitably to the channel characteristic corresponding
to the head, the tape or the recording amplifier, so that it can be
recorded at a limited recording frequency. The output signal from
the channel modulator 23 is amplified by the predetermined level by
the recording amplifier 24 and then recorded on the tape by the
head HD1.
In the case where the playback mode of the high definition VCR 20
is selected by the user, the data stream of the video signal
recorded on the tape is played back by the head HD2 and then
amplified by the predetermined level by the playback
amplification/equalization circuit 25. Also, the playback
amplification/equalization circuit 25 compensates for the
distortion of the amplified data stream. Then, the output signal
from the playback amplification/equalization circuit 25 is
demodulated by the channel demodulator 26 into the state before the
modulation by the channel modulator 23.
The output signal from the channel demodulator 26 is deformatted
into the original state by the deformatter/error correction decoder
circuit 27. Also, the deformatter/error correction decoder circuit
27 corrects an error component of the resultant video signal
generated in the recording and playback.
Then, the error-corrected video signal from the deformatter/error
correction decoder circuit 27 is applied to the decoder 13 in the
high definition television receiver 10 through the switch SW1. The
decoder 13 decodes the received video signal to expand it into the
state before its compression. The decoded video signal from the
decoder 13 is converted into the analog video signal by the D/A
converter 14 and then displayed through the monitor of the high
definition television receiver 10.
Noticeably, an analog video signal of an NTSC or PAL system can be
recorded at a frequency band of 5 MHz on a VCR tape of a VHS
system. Also, in the case of a S-VHS system, the analog video
signal can be recorded at a frequency band of 7 MHz. On the other
hand, a digital video signal receivable by the high definition
television receiver has an information amount much (at least 5
times) more than that of the analog video signal. For this reason,
the digital video signal must be recorded at a density much higher
than that of the analog video signal.
Therefore, the future-oriented high definition VCR can record the
high definition video signal at a very high recording speed on high
quality tapes of MP and ME systems as well as the SVHS system,
differently from the existing analog VCR. Namely, the high
definition video signal can be recorded at a frequency band of 15
MHz by the high definition VCR. By the way, in the high definition
VCR, a channel characteristic or a recording/playback
characteristic of the digital video signal is determined according
to a characteristic of the tape as a recording medium. In this
connection, the digital video signal may recorded and played back
properly when the tape has a small capacity. The improper recording
and playback of the digital video signal results in a degradation
in a picture quality.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in view of the above
problem, and it is an object of the present invention to provide a
signal characteristic variation apparatus for a high definition VCR
in which a characteristic of a video signal transmitted is varied
according to characteristics of a tape and a channel, so that
recording and playback of the video signal can stably be performed,
resulting in prevention of a degradation in a picture quality.
In accordance with the present invention, the above and other
objects can be accomplished by a provision of a signal
characteristic variation apparatus for a high definition video
cassette recorder, comprising scaling means for selecting an output
signal from an encoder or data (variable length-coded motion data,
control data and) from a decoder in a television receiver under a
control of a first switch and formatting the selected signal or
data into a data stream; variable length coding means for coding
the output signal from said encoder or motion data, control data
and DCT coefficient data from said decoder at a variable length and
outputting the coded data to said scaling means; scale control
means for outputting a scale control signal to said scaling means
according to a selected one of recording modes; error correction
coding means for adding an error correction code to an output
signal from said scaling means; formatting means for formatting an
output signal from said error correction coding means in a
recording format on a tape; channel modulation means for modulating
an output signal from said formatting means at a frequency band
suitable to tape and channel characteristics; test signal
generation means for generating a test signal in response to a
switching control signal which is generated according to the
selected recording mode and passing the generated test signal at a
predetermined frequency band, the test signal from said test signal
generation means being used to discriminate the tape and channel
characteristics; recording amplification means for amplifying an
output signal from said channel modulation means or the test signal
from said test signal generation means by a predetermined level
under a control of a second switch; first and second heads for
recording an output signal from said recording amplification means
on the tape; third and fourth heads for playing back a video signal
or the test signal recorded on the tape in a playback mode;
playback amplification means for amplifying the video signal or the
test signal played back by said third and fourth heads by a
predetermined level; tape characteristic detection means for
receiving an output signal from said playback amplification means
under a control of a third switch and discriminating the tape and
channel characteristics in response to the received signal;
equalization means for compensating for a distortion of the output
signal from said playback amplification means in response to a
first output signal from said tape characteristic detection means;
channel demodulation means for demodulating an output signal from
said equalization means at a frequency band suitable to the tape
and channel characteristics in response to a second output signal
from said tape characteristic detection means; deformatting and
error correction decoding means for deformatting an output signal
from said channel demodulation means into the original state and
correcting an error of the resultant data stream; and inverse
scaling means for performing inverse scaling of an output signal
from said deformatting and error correction decoding means to
extract the motion data, the DCT coefficient data and the control
data therefrom and outputting the extracted data to said first
decoding means in the television receiver.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will be more clearly understood from the following
detailed description taken in conjunction with the accompanying
drawings, in which:
FIG. 1 is a block diagram of a convention high definition VCR
connected to a high definition television receiver;
FIG. 2 is a block diagram of a signal characteristic variation
apparatus for a high definition VCR connected to a high definition
television receiver in accordance with an embodiment of the present
invention;
FIG. 3 is a detailed block diagram of a scaler and a variable
length coder in FIG. 2;
FIG. 4 is a detailed block diagram of test signal generation and
tape characteristic detection circuits in FIG. 2;
FIGS. 5 to 9 are views illustrating a process in which a video
signal is compressed according to tape and channel
characteristics;
FIG. 10 is a flowchart illustrating a signal characteristic
variation operation in accordance with the present invention;
and
FIG. 11 is a block diagram of a signal characteristic variation
apparatus for a high definition VCR connected to a high definition
television receiver in accordance with an alternative embodiment of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 2, there is shown a block diagram of a signal
characteristic variation apparatus for a high definition VCR
connected to a high definition television receiver in accordance
with an embodiment of the present invention. In this drawing, the
high definition VCR is designated by the reference numeral 200 and
the high definition television receiver is designated by the
reference numeral 100. The high definition television receiver 100
is adapted to receive a compressed high definition video signal
transmitted from a broadcasting station and display the received
video signal through a monitor (not shown) thereof. The high
definition VCR 200 is adapted to record the high definition video
signal received by the high definition television receiver 100 on a
tape, to play back the high definition video signal recorded on the
tape and to display the played back video signal through the
monitor of the high definition television receiver 100.
The high definition television receiver 100 comprises a tuner 110
for detecting the compressed high definition video signal Vi from
the broadcasting station, received through an antenna (not shown),
and a demodulator 120 for demodulating the detected video signal
from the tuner 110 into a state before its modulation.
A decoder 130 is provided in the high definition television
receiver 100 to extract motion data MV, DCT coefficient data
V.sub.DCT and control data Pctl from the demodulated video signal
from the demodulator 120, decode the extracted data MV, V.sub.DCT
and Pctl at a fixed length and perform inverse quantization and
inverse DCT of the decoded data.
Also, the high definition television receiver 100 comprises a
digital/analog (D/A) converter 140 for converting an output signal
from the decoder 130 into an analog signal.
The high definition VCR 200 comprises an analog/digital (A/D)
converter 210 for receiving an analog video signal AVi from a view
finder of a camera or a camcorder (not shown) and converting the
received analog video signal into a digital video signal, an
encoder 220 for encoding an output signal from the A/D converter
210, a scaler 230 for formatting an output signal form the encoder
220 or the output data MV, V.sub.DCT and Pctl from the decoder 130
in the high definition television receiver 100 into a data stream,
a variable length coder 240 for coding the output signal from the
encoder 220 or the output data MV, V.sub.DCT and Pctl from the
decoder 130 at a variable length and outputting the coded data to
the scaler 230, and a scale controller 250 for outputting a scale
control signal to the scaler 230. The scale control signal from the
scale controller 250 is determined according to a selected one of
recording modes SP, LP and SLP.
Also, the high definition VCR 200 comprises an error correction
coder 260 for adding an error correction code to an output signal
from the scaler 230, a formatter 270 for formatting an output
signal from the error correction coder 260 in a recording format on
the tape, and a channel modulator 280 for modulating an output
signal from the formatter 270 at a frequency band suitable to tape
and channel characteristics.
A test signal generation circuit 290 is provided in the high
definition VCR 200 to generate a test signal in response to a
switching control signal which is generated according to the
selected recording mode and to pass the generated test signal at a
predetermined frequency band. The test signal from the test signal
generation circuit 290 is used to discriminate the tape and channel
characteristics.
A recording amplifier 300 is also provided in the high definition
VCR 200 to amplify an output signal from the channel modulator 280
or the test signal from the test signal generation circuit 290 by a
predetermined level under control of a switch SW14.
Heads HD11 and HD12 are also provided in the high definition VCR
200 to record an output signal from the recording amplifier 300 on
the tape.
Heads HD13 and HD14 are also provided in the high definition VCR
200 to play back a video signal or the test signal recorded on the
tape when a playback mode of the high definition VCR 200 is
selected by the user.
The high definition VCR 200 also comprises a playback amplifier 310
for amplifying the video signal or the test signal played back by
the heads HD13 and HD14 by a predetermined level, a tape
characteristic detection circuit 320 for receiving an output signal
from the playback amplifier 310 under control of a switch SW15 not
shown discriminating the tape and channel characteristics in
response to the received signal, an equalizer 330 for compensating
for distortion of the output signal from the playback amplifier 310
in response to a first output signal from the tape characteristic
detection circuit 320, and a channel demodulator 340 for
demodulating an output signal from the equalizer 330 at a frequency
band suitable to the tape and channel characteristics in response
to a second output signal from the tape characteristic detection
circuit 320.
A deformatter/error correction decoder circuit 350 is also provided
in the high definition VCR 200 to deformat an output signal from
the channel demodulator 340 into the original state and correct an
error of the resultant data stream.
An inverse scaler 360 is also provided in the high definition VCR
200 to perform inverse scaling of an output signal from the
deformatter/error correction decoder circuit 350 to extract the
motion data MV, the DCT coefficient data V.sub.DCT and the control
data Pctl therefrom and output the extracted data MV, V.sub.DCT and
Pctl to the decoder 130 in the television receiver 100 through a
switch SW1.
A decoder 370 is also provided in the high definition VCR 200 to
decode the output data MV, V.sub.DCT and Pctl from the inverse
scaler 360 to expand them into states before their compression.
A D/A converter 380 is also provided in the high definition VCR 200
to convert an output signal from the decoder 370 into an analog
signal and output the analog signal to a monitor (not shown)
connected to the camera or the camcorder.
Referring to FIG. 3, there is shown a detailed block diagram of the
scaler 230 and the variable length coder 240. As shown in this
drawing, the scaler 230 includes a demultiplexer 231 for
demultiplexing the output signal from the encoder 220, a switch
SW11 for selecting one of an output signal from the demultiplexer
231 and the DCT coefficient data V.sub.DCT from the decoder 130, a
switch SW12 for selecting one of the output signal from the
demultiplexer 231 and the control data Pctl from the decoder 130, a
switch SW13 for selecting one of the motion data MV from the
decoder 130 and a ground GND, a DCT coefficient data arrangement
unit 232 for applying an output signal from the switch SW11 to the
variable length coder 240 and compressing the coded DCT coefficient
data from the variable length coder 240 in response to the scale
control signal SCS from the scale controller 250, and a DCT
coefficient data selector 233 for removing unnecessary DCT
coefficient data from an output signal from the DCT coefficient
data arrangement unit 232 in response to the scale control signal
SCS from the scale controller 250.
A control data adjustment unit 234 is provided in the scaler 230 to
apply an output signal from the switch SW12 to the variable length
coder 240, compress the coded control data from the variable length
coder 240 in response to the scale control signal SCS from the
scale controller 250 and adjust a size of the compressed control
data in response to the output signal from the DCT coefficient data
arrangement unit 232.
A motion data adjustment unit 235 is also provided in the scaler
230 to apply an output signal from the switch SW13 to the variable
length coder 240, compress the coded motion data from the variable
length coder 240 in response to the scale control signal SCS from
the scale controller 250 and adjust a size of the compressed motion
data in response to the output signal from the DCT coefficient data
arrangement unit 232.
Also, the scaler 230 includes a multiplexer 236 for multiplexing an
output signal from the DCT coefficient data selector 233 and an
output signal from the control data adjustment unit 234, and a
formatter 237 for formatting an output signal from the multiplexer
236 and an output signal from the motion data adjustment unit 235
into the data stream.
The variable length coder 240 includes a control code table 241 for
storing control data code values for the variable length coding, a
control data converter 242 for converting an output code from the
control code table 241 into control data and outputting the
converted control data to the control data adjustment unit 234 in
the scaler 230, a motion code table 243 for storing motion data
code values for the variable length coding, a motion data converter
244 for converting an output code from the motion code table 243
into motion data and outputting the converted motion data to the
motion data adjustment unit 235 in the scaler 230, a DCT
coefficient code table 245 for storing DCT coefficient data code
values for the variable length coding, and a DCT coefficient data
converter 246 for converting an output code from the DCT
coefficient code table 245 into DCT coefficient data and outputting
the converted DCT coefficient data to the DCT coefficient data
arrangement unit 232 in the scaler 230.
Referring to FIG. 4, there is shown a detailed block diagram of the
test signal generation circuit 290 and the tape characteristic
detection circuit 320. As shown in this drawing, the test signal
generation circuit 290 includes a test signal generator 291 for
generating the test signal in response to the switching control
signal TCS which is generated according to the selected recording
mode, and a band pass filter 292 for passing the generated test
signal from the test signal generator 291 at the predetermined
frequency band and outputting the resultant test signal to the
recording amplifier 300 through the switch SW14.
The tape characteristic detection circuit 320 includes a signal
analyzer 321 for discriminating the tape and channel
characteristics in response to the output signal from the playback
amplifier 310 and controlling the scale controller 250 in
accordance with the discriminated result, a comparator 322 for
comparing a frequency characteristic of an output signal from the
signal analyzer 321 with that of the test signal from the test
signal generation circuit 290 and applying the second output signal
to the channel modulator 280 and the channel demodulator 340 in
accordance with the compared result to adjust the frequency bands
thereof, and a tape characteristic measurement unit 323 for
detecting an error of the played back test signal in response to an
output signal from the comparator 322, varying a filter coefficient
of the band pass filter 292 in such a manner that the detected
error becomes smaller than a predetermined threshold value and
outputting the varied filter coefficient as the first output signal
to the equalizer 330 to determine a filter coefficient thereof.
The operation of the high definition VCR with the above-mentioned
construction in accordance with the embodiment of the present
invention will hereinafter be described in detail with reference to
FIGS. 2 to 10.
First, in the high definition television receiver 100, the
compressed high definition video signal Vi transmitted from the
broadcasting station is detected by the tuner 110 and then
demodulated by the demodulator 120. The demodulated video signal
from a demodulator 120 is decoded at the fixed length and then
deformatted by the decoder 130. Namely, the decoder 130 extracts
the motion data MV, the DCT coefficient data V.sub.DCT and the
control data Pctl from the demodulated video signal from the
demodulator 120, decodes the extracted data MV, V.sub.DCT and Pctl
at the fixed length and performs the inverse quantization and
inverse DCT of the decoded data. The resultant digital video signal
from the decoder 130 is applied to the D/A converter 140. Also, the
extracted motion data MV, DCT coefficient data V.sub.DCT and
control data Pctl from the decoder 130 are applied to the scaler
230 in the high definition VCR 200 through the switch SW1.
In the case where the high definition television receiver 100 is
selected by the user, the digital video signal from the decoder 130
is applied to the D/A converter 140 through the switch SW1 and then
converted into the analog video signal thereby. The analog video
signal from the D/A converter 140 is displayed through the monitor
of the television receiver 100.
On the other hand, in the case where the recording mode of the high
definition VCR 200 is selected by the user, the switching control
signal TCS is generated according to the selected recording mode
and then applied to the test signal generation circuit 290. In the
test signal generation circuit 290, the test signal generator 291
generates the test signal indicative of the tape and channel
characteristics in response to the switching control signal TCS.
The test signal from the test signal generator 291 is passed at the
predetermined frequency band by the band pass filter 292 and then
applied to the recording amplifier 300 through the switch SW14. As
a result, the resultant test signal from the test signal generation
circuit 290 is amplified by the recording amplifier 300 and then
recorded on the tape by the heads HD11 and HD12.
Then, the playback mode of the high definition VCR 200 is set upon
completion of the recording of the test signal. In this case, the
test signal detected by the heads HD13 and HD14 is amplified by the
predetermined level by the playback amplifier 310 and then applied
to the tape characteristic detection circuit 320 through the switch
SW15 depending on the switching control signal TSC.
In the tape characteristic detection circuit 320, the signal
analyzer 321 analyzes the output signal from the playback amplifier
310 to discriminate the tape and channel characteristics. The scale
control signal from the scale controller 250 is applied to the
scaler 230, being varied as a result of the analysis by the signal
analyzer 321.
Also in the tape characteristic detection circuit 320, the
comparator 322 compares the frequency characteristic of the output
signal from the signal analyzer 321 with that of the test signal
from the test signal generation circuit 290 to discriminate the
tape characteristic and the channel characteristic or a
recording/playback characteristic. As a result of the comparison,
the comparator 322 applies the second output signal to the channel
modulator 280 and the channel demodulator 340 to adjust the
frequency bands thereof. Therefore, the channel modulator 280 and
the channel demodulator 340 perform the modulation and demodulation
at the frequency bands suitable to the tape and channel
characteristics.
The output signal from the comparator 322 is also applied to the
tape characteristic measurement unit 323. In the tape
characteristic measurement unit 323, the error .epsilon.i is
greater than the predetermined threshold value .epsilon..sub.TH,
then it is compared with a minimum allowable value .epsilon.min. In
this case, if the minimum allowable value .epsilon.min is greater
than the detected error .epsilon.i, it is set as the detected error
.epsilon.i with respect to a certain frame, thereby causing the
filter coefficient of the band pass filter 292 to be adjusted.
Then, the test signal from the test signal generator 291 is passed
through the band pass filter 292 at the adjusted filter coefficient
and then applied to the recording amplifier 300 through the switch
SW14. As a result, the test signal from the test signal generation
circuit 290 is amplified by the recording amplifier 300 and then
recorded on the tape by the heads HD11 and HD12. Again, the test
signal recorded on the tape is applied to the tape characteristic
detection circuit 320 through the playback amplifier 310 and the
switch SW15. In the tape characteristic detection circuit 320, the
signal analyzer 321 analyzes the output signal from the playback
amplifier 310 to discriminate the tape and channel characteristics.
The scale control signal from the scale controller 250 is applied
to the scaler 230, being varied as a result of the analysis by the
signal analyzer 321. Also in the tape characteristic detection
circuit 320, the comparator 322 compares the frequency
characteristic of the output signal from the signal analyzer 321
with that of the test signal from the test signal generation
circuit 290 to discriminate the tape and channel characteristics.
As a result of the comparison, the comparator 322 applies the
second output signal to the channel modulator 280 and the channel
demodulator 340 to adjust the frequency bands thereof. The output
signal from the comparator 322 is also applied to the tape
characteristic measurement unit 323. Then, the tape characteristic
measurement unit 323 detects the error .epsilon.i of the test
signal passed at the varied filter coefficient in response to the
output signal from the comparator 322. If the detected error
.epsilon.i is greater than the predetermined threshold value
.epsilon..sub.TH, the above operation is repeatedly performed.
In other words, the error of the test signal passed through the
band pass filter 292 at the varied filter coefficient is detected
and then compared with the predetermined threshold value
.epsilon..sub.TH in the tape characteristic measurement unit 323.
If the detected error .epsilon.i of the test signal is smaller than
the predetermined threshold value .epsilon..sub.TH, the filter
coefficient of the band pass filter 292 is applied to the equalizer
330 for adjustment of the filter coefficient thereof. On the
contrary, if the detected error .epsilon.i of the test signal is
greater than the predetermined threshold value .epsilon..sub.TH,
the above operation is repeatedly performed until the detected
error .epsilon.i of the test signal becomes smaller than the
predetermined threshold value .epsilon..sub.TH.
In this manner, in the case where the recording mode of the high
definition VCR 200 is selected by the user, contacts "a" of the
switches SW14 and SW15 are connected to contacts c thereof for a
predetermined time period in response to the switching control
signal so that the tape and channel characteristics can be
detected, and the frequency bands of the channel modulator 280,
equalizer 330 and channel demodulator 340 are determined in
accordance with the detected result. Also, the scale control signal
from the scale controller 250 is controlled in accordance with the
detected result. Thereafter, after the lapse of the predetermined
time period, contacts "b" of the switches SW14 and SW15 are
connected to contacts a thereof. As a result, the recording and
playback of the video signal are performed.
First, the analog video signal AVi from the view finder of the
camera or the camcorder is received and then converted into the
digital video signal by the A/D converter 210. The encoder 220
encodes the output signal from the A/D converter 210 suitably to
the recording format.
The scale control signal SCS from the scale controller 250 is
applied to the scaler 230 according to the selected one of the
recording modes SP, LP and SLP. The scaler 230 selects the output
signal from the encoder 220 or the output data MV, V.sub.DCT and
Pctl from the decoder 130 in the high definition television
receiver 100 through the switch SW1 and formats the selected signal
or data into the data stream in response to the scale control
signal SCS from the scale controller 250.
Namely, as shown in FIG. 3, in the scaler 230, the demultiplexer
231 demultiplexes the output signal from the encoder 220 for data
separation therefrom. In response to the switching control signal,
the switch SW11 selects one of the separated data from the
demultiplexer 231 and the DCT coefficient data V.sub.DCT from the
decoder 130 and the switch SW12 selects one of the separated data
from the demultiplexer 231 and the control data Pctl from the
decoder 130. Also, the switch SW13 selects one of the motion data
MV from the decoder 130 and the ground GND.
The output data from the switch SW11 is applied to the DCT
coefficient code table 245 in the variable length coder 240.
Outputted from the DCT coefficient code table 245 is a code value
corresponding to the output data from the switch SW11. Namely, the
output data from the switch SW11 is coded at a variable length at a
compression rate determined by the scale control signal from the
scale controller 250. The DCT coefficient code from the DCT
coefficient code table 245 is converted into the DCT coefficient
data by the DCT coefficient data converter 246 in the variable
length coder 240.
The converted DCT coefficient data from the DCT coefficient data
converter 246 is applied to the DCT coefficient data arrangement
unit 232 in the scaler 230 and then arranged thereby for the
formatting of the data stream. The size of the arranged DCT
coefficient data is adjusted by the scale control signal from the
scale controller 250.
The DCT coefficient data selector 233 in the scaler 230 is adapted
to remove unnecessary DCT coefficient data from the output signal
from the DCT coefficient data arrangement unit 232 in response to
the scale control signal SCS from the scale controller 250. Namely,
pixel resolution is performed to reduce the size of the variable
length-coded DCT coefficient data, as shown in FIGS. 5 to 9, which
are views illustrating a process in which the video signal is
compressed according to the tape and channel characteristics.
The output data from the switch SW12 is applied to the control code
table 241 in the variable length coder 240, which outputs a control
code value corresponding to the output data from the switch SW12.
The control code value from the control code table 241 is converted
into the control data by the control data converter 242 in the
variable length coder 240.
Then, the control data from the control data converter 242 is
applied to the control data adjustment unit 234 in the scaler 230.
The control data adjustment unit 234 compresses the control data
from the control data converter 242 in response to the scale
control signal SCS from the scale controller 250 and adjusts the
size of the compressed control data in response to the output
signal from the DCT coefficient data arrangement unit 232.
The output data from the switch SW13 is applied to the motion code
table 243 in the variable length coder 240, which outputs a motion
code value corresponding to the output data from the switch SW13.
The motion code value from the motion code table 243 is converted
into the motion data by the motion data converter 244 in the
variable length coder 240.
Then, the motion data from the motion data converter 244 is applied
to the motion data adjustment unit 235 in the scaler 230. The
motion data adjustment unit 235 compresses the motion data from the
motion data converter 244 in response to the scale control signal
SCS from the scale controller 250 and adjusts the size of the
compressed motion data in response to the output signal from the
DCT coefficient data arrangement unit 232.
Subsequently, the multiplexer 236 in the scaler 230 multiplexes the
output signal from the DCT coefficient data selector 233 and the
output signal from the control data adjustment unit 234. The
formatter 237 in the scaler 230 formats the output signal from the
multiplexer 236 and the output signal from the motion data
adjustment unit 235 into the data stream.
The data stream from the scaler 230 is sent to the error correction
coder 260, which adds the error correction code to the data stream
from the scaler 230. The formatter 270 formats the output signal
from the error correction coder 260 in the recording format on the
tape.
The output signal from the formatter 270 is modulated by the
channel modulator 280 at the frequency band determined by the
output signal from the comparator 322 in the tape characteristic
detection circuit 320, and then applied to the recording amplifier
300 through a contact "b" of the switch SW14. As a result, the
output signal from the channel modulator 280 is amplified by the
recording amplifier 300 and then recorded on the tape by the heads
HD11 and HD12.
In the case where the playback mode of the high definition VCR 200
is selected by the user, the data stream of the video signal
recorded on the tape is played back by the heads HD13 and HD14 and
then amplified by the playback amplifier 310. The output signal
from the playback amplifier 310 is applied to the equalizer 330
through the contact "b" of the switch SW15.
The equalizer 330 is adapted to compensate for the distortion of
the output signal from the playback amplifier 310 in response to
the output signal from the tape characteristic measurement unit 323
in the tape characteristic detection circuit 320. The output signal
from the equalizer 330 is demodulated by the channel demodulator
340 at the frequency band determined by the output signal from the
comparator 322 in the tape characteristic detection circuit 320.
The output signal from the channel demodulator 340 is applied to
the deformatter/error correction decoder circuit 350.
The deformatter/error correction decoder circuit 350 deformats the
output signal from the channel demodulator 340 into the original
state and then corrects the error of the resultant data stream. The
inverse scaler 360 functions to perform the inverse scaling of the
output signal from the deformatter/error correction decoder circuit
350 to extract the motion data MV, the DCT coefficient data
V.sub.DCT and the control data Pctl therefrom. The extracted data
MV, V.sub.DCT and Pctl from the inverse scaler 360 is applied to
the decoder 130 in the television receiver 100 through the switch
SW1. The decoder 130 decodes the output data MV, V.sub.DCT and Pctl
from the inverse scaler 360 to expand them into the states before
their compression. The resultant digital video signal from the
decoder 130 is applied to the D/A converter 140 and then converted
into the analog video signal thereby. Then, the analog video signal
from the D/A converter 140 is displayed through the monitor of the
television receiver 100.
Also, the extracted data MV, V.sub.DCT and Pctl from the inverse
scaler 360 is applied to the decoder 370. The decoder 370 decodes
the output data MV, V.sub.DCT and Pctl from the inverse scaler 360
to expand them into the states before their compression. The
resultant digital video signal from the decoder 370 is applied to
the D/A converter 380 and then converted into the analog video
signal thereby. Subsequently, the analog video signal from the D/A
converter 380 is displayed through the monitor connected to the
camera or the camcorder.
The above-mentioned operation of the high definition VCR will
hereinafter be described in more detail with reference to FIG. 10,
which is a flowchart illustrating a signal characteristic variation
operation in accordance with the present invention.
First, if the recording mode of the high definition VCR is selected
by the user, the contact "a" of the switch SW14 is connected to the
contact "c" thereof and, at the same time, the test signal is
generated. The generated test signal is recorded on the tape in a
still mode.
Upon completion of the recording of the test signal on the tape,
the recording mode is stopped and the playback of the recorded test
signal is started. In this case, the contact a of the switch SW15
is connected to the contact "c" thereof and the recorded test
signal is played back in the still mode. The played back test
signal is analyzed.
The tape and channel characteristics are discriminated on the basis
of the analysis of the played back test signal, and the scale
controller 250 and the channel modulator 280 are controlled in
accordance with the discriminated result. Therefore, the input
video data is modulated at the frequency band suitable to the tape
and channel characteristics and then recorded on the tape.
On the other hand, in the case where the playback mode of the high
definition VCR is selected by the user, the test signal recorded on
the tape is amplified by the playback amplifier 310 and then
applied to the tape characteristic detection circuit 320 through
the contact "c" of the switch SW15. The tape and channel
characteristics are discriminated on the basis of the analysis of
the played back test signal. Upon completion of the analysis of the
played back test signal, the contact b of the switch SW15 is
connected to the contact "a" thereof.
In this case, the error .epsilon.i of the played back test signal
is detected and then compared with the predetermined threshold
value .epsilon..sub.TH. If the detected error .epsilon.i of the
test signal is smaller than the predetermined threshold value
.epsilon..sub.TH, the tape characteristic is measured and the
filter coefficient of the band pass filter 292 is then adjusted. On
the other hand, if the detected error .epsilon.i is greater than
the predetermined threshold value .epsilon..sub.TH, then it is
compared with the minimum allowable value .epsilon.min. In this
case, if the minimum allowable value .epsilon.min is greater than
the detected error .epsilon.i, it is set as the detected error
.epsilon.i and the filter coefficient of the band pass filter 292
is then adjusted.
Then, the test signal passed through the band pass filter 292 at
the adjusted filter coefficient is recorded on the tape, and the
error thereof is again detected and compared with the minimum
allowable value .epsilon.min. If the detected error .epsilon.i of
the test signal is smaller than the minimum allowable value
.epsilon.min, the above operation is repeatedly performed until the
detected error .epsilon.i of the test signal becomes greater than
the minimum allowable value .epsilon.min. At that time that the
detected error .epsilon.i of the test signal becomes greater than
the minimum allowable value .epsilon.min, the filter coefficient of
the equalizer 330 is determined according to the filter coefficient
of the band pass filter 292.
With the tape and channel characteristics analyzed through the
above-mentioned operation, the scale controller 250, the channel
modulator 280, the equalizer 330 and the channel demodulator 340
are controlled so that the video data can be modulated and
demodulated at the frequency bands suitable to the tape and channel
characteristics and then recorded and played back on/from the
tape.
Alternatively, the video data decoded at the fixed length by the
decoder 130 in the television receiver 100 may be applied to the
scaler 230 in the high definition VCR 200. In this case, the scaler
230 formats the decoded video data from the decoder 130 into the
data stream and then applied the data stream to the variable length
coder 240. Then, the variable length-coded video data from the
variable length coder 240 is received by the error correction coder
260.
Referring to FIG. 11, there is shown a block diagram of a signal
characteristic variation apparatus for a high definition VCR
connected to a high definition television receiver in accordance
with an alternative embodiment of the present invention. In this
embodiment, it is assumed that the error correction code is
compressed and transmitted by the broadcasting station, being added
to the video signal. In this connection, the construction of this
drawing is the same as that of FIG. 2, with the exception that the
error correction coder 260 is removed and the deformatter/error
correction decoder circuit 350 is replaced by only a deformatter
350'.
In operation, the scaler 230 formats the compressed data extracted
by the television receiver 100 or the output signal from the
encoder 220 into the data stream and then applies the data stream
to the formatter 270. The formatter 270 formats the output signal
from the scaler 230 in the recording format on the tape. The
procedure of recording the output signal from the formatter 270 on
the tape is the same as that in the first embodiment of FIG. 2 and
a detailed description thereof will thus be omitted.
In the playback of the video data recorded on the tape, the output
signal from the channel demodulator 340 is applied to the
deformatter 350'. The deformatter 350' functions to deformat the
output signal from the channel demodulator 340 into the original
state. The procedure of displaying the output signal from the
deformatter 350' through the monitor of the television receiver 100
or the monitor connected to the camera or the camcorder is the same
as that in the first embodiment of FIG. 2 and a detailed
description thereof will thus be omitted.
Noticeably, the error of the output signal from the inverse scaler
360 is extracted and corrected on the basis of the error correction
code transmitted from the broadcasting station by the decoder 130
in the television receiver. In other words, in the second
embodiment of the present invention, the decoder 130 in the
television receiver 100 is adapted to extract and correct the error
inserted in the transmission and reception of the video data or
generated in the recording and playback of the high definition
VCR.
As apparent from the above description according to the present
invention, the test signal of the predetermined frequency band is
recorded and played back on/from the tape for discrimination of the
tape and channel characteristics in the recording mode. Therefore,
the video signal can stably be recorded on the tape with its
characteristic adjusted according to the discriminated tape and
channel characteristics. Also, in the playback mode, the tape and
channel characteristics are discriminated by detecting the test
signal recorded on the tape. Therefore, the video signal can stably
be played back from the tape with its frequency characteristic
adjusted according to the discriminated tape and channel
characteristics.
Although the preferred embodiments of the present invention have
been disclosed for illustrative purposes, those skilled in the art
will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *